DIVERSITE DES RHIZOBACTERIES DE LA RHIZOSPHERE DES GENOTYPES D ANACARDIER (ANACARDIUM OCCIDENTALE L.)TOP 24 DE LA STATION DE RECHERCHE DE LATAHA (CNRA) ET CARACTERISATION DE LEUR POTENTIEL DANS LA PROMOTION DE LA CROISSANCE DES PLANTES (PGPR)
Abstract
Rhizobacteria play a major role in the functioning of agricultural ecosystems by contributing to plant nutrition and growth. However, information regarding the diversity and functional properties of bacteria associated with cashew genotypes in plot Top 24 in Lataha remains limited. This study aimed to characterize these bacterial communities and assess their potential as plant growth-promoting bacteria (PGPR). Rhizosphere soil samples were collected from cashew genotypes in plot Top 24 and from citrus trees located on the periphery. The physicochemical properties of the soils were determined,and bacteria were isolated on LB and characterized by Gram staining and biochemical tests. The main PGPR traits evaluated included phosphate solubilization, the production of indole -3- acetic acid (IAA), ammonia (NH3), and hydrocyanic acid (HCN), atmospheric nitrogen fixation, as well as nitrate reductase and urease activities. The soils studied were generally acidic (pH ranging from 3.71 to 5.24) with variations in moisture and electrical conductivity depending on the rhizosphere. Twenty-five bacterial isolates were obtained, including 21 from cashew genotypes and 4 from citrus. The majority of the strains were Gram-negative bacilli and exhibited catalase and oxidase activity. PGPR assays revealed no phosphate solubilization or HCN production, while several isolates produced AIA and a high proportion exhibited nitrogen-fixing ability and nitrate reductase activity.